A standard-value-based comparison tool to analyze U.S. soil regulations for the top 100 concerned pollutants

Residential surface soil contamination is often addressed by the use of regulatory guidance values (RGVs), which specify the maximum allowed concentration that can be present without prompting a regulatory action. In the U.S., there are at least 72 jurisdictions, including national, state, and regional, that have published guidance values for one or more of the one hundred most frequently regulated chemicals. A standard-value-based comparison tool in this study is developed to analyze values from 40 states and from the U.S. Environmental Protection Agency (U.S. EPA). The comparison tool can help evaluate the completeness of RGV sets, quantify the average deviation of RGVs from worldwide central tendencies, and measure the overall difference between the numbers of RGVs above and below central tendencies. The pollutants considered in this study include benzidines/aromatic amines, dioxins and polychlorinated biphenyls (PCBs), hydrocarbons, inorganic substances, nitroamines/ethers/alcohols, organophosphates and carbamates, pesticides, phenols/phenoxy acids, phthalates, and volatile organic compounds. Based on completeness and comparisons of order of magnitude variations, five types of scores are generated. The results from the completeness scores indicate that some states lack soil RGVs for the top 100 concerned pollutants. The results from the comparison scores indicate that some jurisdictions have provided the RGVs averagely deviating from worldwide central tendencies and U.S. EPA scores by over two orders of magnitude, which might be beyond the risk model variabilities and increase human health risks. Hopefully, the regulatory comparison tool developed in this study will help risk assessors and regulatory scientists to better evaluate soil standards and protect public health.